1. Field of the Invention
The present invention relates to an optoelectronic switching network intended for switching optical signals.
2. Description of the Prior Art
Optoelectronic switching networks are known particulaly from the U.S. Patent Application Ser. No. 196,083 filed July 8, 1980, now U.S. Pat. No. 4,437,190 for switching signals conveyed by optically modulated light beams. These switching networks comprise:
a transmit board formed of a plurality of transmit units each including a light source, the light sources are respectively linked to incoming lines and arranged in matrix-form on the transmit board;
a receive board formed of a plurality of receive units each including a plurality of optoelectronic detectors or cells, the optoelectronic detectors are respectively linked to outgoing lines and arranged in matrix-form in the receive unit; and
optical means for projecting the transmit board image onto each of the receive units such that the light source images coincide with the optoelectronic detectors of the receive units.
By assigning A, B, C, D, . . . to subscribers connected to the switching network via incoming and outgoing lines, the light sources and the receive units corresponding to these subscribers, and by assigning a, b, c, d, . . . to the optoelectronic detectors of each receive unit, all the detectors a to d of the receive unit A can be selectively connected to the subscriber A, all the detectors a to d of the receive unit B can be selectively connected to the subscriber B, all the detectors a to d of the receive unit C can be selectively connected to the subscriber C and all the detectors a to d of the receive unit D can be selectively connected to the subscriber D. A bilateral communication between the subscribers A and B runs in one direction via the source A and the optoelectronic detector a of the receive unit B and in the other direction via the source B and the optoelectronic detector b of the receive unit A.
The transmit board in the prior art optoelectronic switching network comprises additional sources connected to tone generators and dialing generators. The receive units comprise additional optoelectronic detectors corresponding to these sources and which coincide with the images of the said additional sources via the optical means. Lastly, the receive board comprises an additional receive unit referred to as functionally connected to a central control unit.
As a result of the functional receive unit, the central control unit can supervise the transmit board sources by scanning the functional receive unit optoelectronic detectors and by taking account of the fact that when a transmit board source is illuminated, this corresponds to an active optoelectronic detector.
Thus as is seen in a recap on the former art which will be made later, the connection in a receive unit of a given detector a to d to the output line from this receive unit comes about locally at the very receive unit stage with no intervention on the part of the central control unit. The latter central control unit therefore has no supervision over the receive unit optoelectronic detectors as it has over the transmit board sources through the functional receive unit.